Managing the Software-Defined WAN

cloud management network server
Credit: Computerworld UK

New intelligence in the WAN may require a new approach to management

In previous articles I discussed how SD-WAN is an attractive step forward from simple IPsec VPNs as well as multi-vendor, multi-technology hybrid WANs, driving new functionality and quality levels into these networks. One important question is how next-generation WANs are managed – and by whom.

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Management is a fairly broad subject – what does it consist of in this context? There’s the orchestrator, where the configuration profiles and policies for each device reside. This can be cloud hosted or deployed on-premise, but somebody needs to perform the service design and configuration management roles regardless of where it resides. There are the edge devices themselves, which are typically managed through the orchestrator’s southbound interface. And finally there are the difficult, fragmented components around the edges: ISPs, MPLS vendors, metro Ethernet providers, maintenance vendors, field engineering resources – all of these must be effectively managed to deliver a workable solution.

Out with the old?

Let’s not forget that many enterprises are heavily invested in network management infrastructure and tools. This is a very mature industry, and one of the first surprises for the enterprise is often how different the management model looks in an SD-WAN solution.

Consider the following SNMP-based polling mechanism used by enterprises and MSPs to monitor and manage millions of traditional network devices today:

Traditional network management Ciaran Roche

Traditional network management approach

In an SD-WAN solution, the edge routers are typically replaced with x86 servers running a customized version of Linux and a software-based router on top of it. Some vendors do expose an SNMP interface, but the devices look much more like the servers they are than network endpoints. To get the full picture of what’s happening on the network, a very different approach is used:

SD-WAN network management Ciaran Roche

The biggest difference? The NMS now communicates with the orchestrator, rather than the devices themselves. The interface is usually bi-directional, allowing events to be pushed from the orchestrator to the NMS, as well as queries from the NMS to the orchestrator.

This is a major architectural change (and arguably a huge increase in functionality), and for many enterprises it means their existing network management systems aren’t up to the task. Fortunately the orchestrator interfaces themselves are often highly functional, allowing even larger WANs to be managed from a modern browser-based GUI interface. In many cases, the application and device-level reporting in the orchestrator interface is significantly more functional than the enterprise had in its traditional network. This is resulting in a big change in the life cycle management approach for these networks.

Who does the work?

The simple, user-friendly interfaces in many SD-WAN orchestrator platforms can mask some of the broader management complexities that enterprises need to consider when deploying this technology. In fact, these networks require that many of the same roles that existed in traditional networks to be identified and staffed appropriately to drive a successful outcome. Just as with traditional networks, there are functions that are better suited to being retained internally vs. out-tasked or outsourced:

SD-WAN management responsibilities Ciaran Roche

SD-WAN management responsibilities

It can clearly be seen from this chart that a “managed SD-WAN” environment encompasses much more than assigning responsibility for monitoring and managing the devices. Different organizations will have different appetites for performing various functions internally vs. externally, but the ownership of each function in the network life cycle needs to be carefully considered.

Enterprises out-tasking or outsourcing functions in this life cycle often run into issues working with “legacy” providers. Not all managed service providers are well positioned to manage newer technology solutions like SD-WAN, especially if it needs to coexist with other traditional network components (i.e., not a ‘greenfield’ environment). Identifying a partner that can operate effectively while providing the agility to keep up with this rapidly-changing technology is an important consideration.

External vendor management

Let’s return to one of the critical, but often overlooked aspects of a managed SD-WAN environment. For many enterprises, one of the major drivers for adopting this technology is the ability to use Internet-based infrastructure in the WAN while addressing some of the inherent Internet performance challenges. While this can be true, a side effect is the dependency on these underlying Internet circuits and other infrastructure becomes far more critical than before. Local vendors typically offer the best price/performance ratio, but it’s easy for an enterprise to find itself with dozens or even hundreds of ISPs that need to be managed as a result.

Incorporating an effective life cycle management methodology for external vendors is an important part of deploying next-generation technologies like SD-WAN. The enterprise may have trading relationships with many small ISPs, each providing just a handful of circuits and with only a basic contract in place, but a failure in this environment can have significant consequences if not well managed. This function needs to be carefully considered when planning the SD-WAN management and life cycle model.

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